NHA Phlebotomy Certification Practice Exam

Which type of blood sample is most commonly used for glucose testing?

1. Serum

2. Whole blood

3. Plasma

4. Capillary blood

The correct answer is: Serum

The most commonly used type of blood sample for glucose testing is serum. Serum is the liquid portion of the blood that remains after coagulation, which means it does not contain cells or clotting factors. When glucose levels are measured, serum is preferred as it provides a clear sample that reflects the concentration of glucose in the blood without interference from the components that can be found in whole blood, such as red blood cells and platelets. Serum glucose testing has several advantages: it is more stable for certain analyses, can be stored longer, and is less prone to variations during the testing process compared to other types of samples. In many clinical laboratories, tests for glucose are routinely performed on serum samples to ensure accurate and reliable results. While whole blood, plasma, and capillary blood can also be used for glucose testing, they are not the standard approach used in laboratory settings. Whole blood contains all components of blood, including cells, which can complicate glucose measurement due to dilution effects. Plasma, which is obtained after centrifuging whole blood with anticoagulants, is also used for glucose testing but is less common than serum. Capillary blood, typically collected via fingerstick, is often used in point-of-care testing settings but is not as